Coaxial plug connectors are known from U.S. Pat. No. 4,548,453 which are mountable and electrically connectable to a circuit panel and which are right-angled to mate with receptacle connectors parallel to the circuit panel. Such right-angled plug connectors are useful to replace coaxial cable leads in coaxial patchboard systems for automatic test equipment for testing electronic circuit boards or cards. The inner or signal contact is right angled with a vertical portion extending downwardly from the conductive housing near its rearward end to be connected to a signal path of the circuit panel, while the horizontal portion extends forwardly from the front end to mate with a corresponding signal contact of a receptacle connector; premolded tubular dielectric plastic sleeves are placed over the horizontal and vertical contact portions. An outer ground contact extends coaxially around the insulated horizontal portion of the signal contact with a forward section extending from the conductive housing to mate with a corresponding ground contact of the receptacle connector. The rearward section of the outer ground contact is mechanically and electrically joined to the conductive housing, and a ground post extends downwardly from proximate the front end of the housing to be joined to a ground path of the circuit panel. One typical coaxial cable used with such a coaxial patchboard system is type RG-174/U and has a nominal impedance of 50 ohms.
It is desirable that a coaxial plug connector match or at least approximate the characteristic impedance of the cable, and the prior art connector disclosed in U.S. Pat. No. 4,548,453 does not optimize its ability to approximate the cable impedance. In practice, the inner and outer surfaces of the premolded dielectric sleeves are not consistently concentric about the contact-receiving bore therethrough, which affects impedance control of the assembled connector in use. Thinner-walled areas of the premolded sleeves are believed to result in areas of low impedance along the contact if it results in reduced separation between the inner and outer contacts, detracting from achievement of impedance control and matching. Also, the forward contact structure which mates with the receptacle connector has substantially lower impedance therealong than the cable, which compounds the impedance mismatch already existing due to the discontinuity of the connector and the right-angle bend.
It is also desirable to provide a dielectric covering around at least portions of the inner contact for radial spacing of the outer contact, which portions are secured in place along the inner contact without the necessity for structural features of the inner contact such as stop shoulders or projections which would act to lower the impedance or serve to reflect current or voltage or both, and without the necessity for tedious assembly including axially locating the covering along the contact and bonding it thereto.
It is further desirable to reduce reflection produced by a coaxial plug connector.
It is yet desirable that a coaxial plug connector be adapted to be mounted on a circuit panel whose contact-receiving holes may be slightly imprecisely arrayed so that the plurality of such coaxial plug connectors already in mated relationship with a multi-terminal receptacle connector can then be mounted on the circuit panel by its contacts being insertable into the circuit panel holes.